将分页光标和其他功能添加到端点结果

时间：2015-12-19 19:42:04

标签： node.js loopbackjs strongloop

Strongloop api非常适合开箱即用。但是我目前正在尝试进行一些自定义。我正在尝试向category模型添加一个远程方法，该方法与端点数据一起返回以下内容：perPage，total，paging（详细信息如下所示） 。对于paging，before和after是基于gameId的参数。如果值为limit或大于5，则null将默认为5。什么是追加前面提到的结果的最佳方式？

例如，http://localhost:3000/api/Categories/1004/games/mature?before=1000053将返回所有gameId小于1000053且before所有gameIds大于1000053的所有 Category.findById(id, {}, function(err, category){ if (err) return callback(err); //set limit if (limit && limit > 5){ limit = 5; }else if(limit === undefined){ limit = 5; } //set after cursor Games.find({ "where": { categoryId: id, mature: true, gameId: {gt: after} }, "limit": limit }, function(err, gameArr) { if (err) return callback(err); callback(null, gameArr); }); }); 。

  

公共/模型/ category.js 

/Categories/1004/games/mature

{ “perPage”: 5, //value from limit “total”: 5, //total of return items from array "data": [ ... Endpoint data is here ], "paging": { "cursors": { "after": 1000057, //last item in array "before": 1000053 //first item in array }, "previous": "http://localhost:3000/api/Categories/1004/games/mature?before=1000053" //url for previous "next": "http://localhost:3000/api/Categories/1004/games/mature?after=1000057" //url for after } }

的结束点结果 
{{1}}

2 个答案:

答案 0 :(得分：2)

这里的问题是你使用Category模型作为入口点，当你看起来应该使用Game模型的内置查询方法时带有过滤器和限制和偏移，完全停止。这将允许您分页，而无需添加所有这些复杂性来支持您的前/后概念。这是不必要的。 如果您的关系设置正确，那么您在游戏中分页的所有内容都是游戏模型查询！

例如，您似乎需要在特定类别中成熟的分页游戏列表，对吧？要使用这些条件获得5个游戏的结果，您需要发送一个json REST API调用，如下所示：

http://0.0.0.0:3000/api/Games?filter=%7B%20%22where%22%3A%20%7B%22mature%22%3Atrue%2C%20%22categoryId%22%3A%201004%7D%2C%20%22offset%22%3A%200%2C%20%22limit%22%3A%205%20%7D

由于它的编码很难阅读，但底层过滤器的构造如下：

{ "where": {"mature":true, "categoryId": 1004}, "offset": 0, "limit": 5 }

这将返回以下数据集，即 1004 categoryId中的前5个游戏，也是成熟的：

[
  {
    "mature": true,
    "gameName": "CODBlacOps3",
    "categoryId": 1004,
    "gameId": 1000053,
    "description": "Published by Activision",
    "publishedDate": "2015-01-01T00:00:00.000Z"
  },
  {
    "mature": true,
    "gameName": "Evolve",
    "categoryId": 1004,
    "gameId": 1000054,
    "description": "Published by Turtle Rock Studios",
    "publishedDate": "2015-01-01T00:00:00.000Z"
  },
  {
    "mature": true,
    "gameName": "Battlefield4",
    "categoryId": 1004,
    "gameId": 1000055,
    "description": "Published by EA Digital Illusions",
    "publishedDate": "2013-01-01T00:00:00.000Z"
  },
  {
    "mature": true,
    "gameName": "Rainbow6",
    "categoryId": 1004,
    "gameId": 1000056,
    "description": "Published by EUbisoft",
    "publishedDate": "2015-01-01T00:00:00.000Z"
  },
  {
    "mature": true,
    "gameName": "Destiny",
    "categoryId": 1004,
    "gameId": 1000057,
    "description": "Published by Bungie",
    "publishedDate": "2014-01-01T00:00:00.000Z"
  }
]

要获得5个游戏的下一页，我们只需将偏移量更改为5，这会告诉数据库跳过前5个，因为我们现在在第2页上：< / p> 

{ "where": {"mature":true, "categoryId": 1004}, "offset": 5, "limit": 5 }

返回以下结果：

[
  {
    "mature": true,
    "gameName": "Wolfenstein",
    "categoryId": 1004,
    "gameId": 1000058,
    "description": "Published by Bethesda",
    "publishedDate": "2014-01-01T00:00:00.000Z"
  },
  {
    "mature": true,
    "gameName": "StarWarsBattleFront",
    "categoryId": 1004,
    "gameId": 1000059,
    "description": "Published by EA DICE",
    "publishedDate": "2015-01-01T00:00:00.000Z"
  },
  {
    "mature": true,
    "gameName": "Test1",
    "categoryId": 1004,
    "gameId": 1000060,
    "description": "Published by Test1",
    "publishedDate": "2015-12-19T00:00:00.000Z"
  },
  {
    "mature": true,
    "gameName": "Test2",
    "categoryId": 1004,
    "gameId": 1000061,
    "description": "Published by Test2",
    "publishedDate": "2015-12-19T00:00:00.000Z"
  },
  {
    "mature": true,
    "gameName": "Test3",
    "categoryId": 1004,
    "gameId": 1000062,
    "description": "Published by Test3",
    "publishedDate": "2015-12-19T00:00:00.000Z"
  }
]

默认情况下，游戏按照game_id的顺序排列。没有自定义远程方法和嵌套的find（）！

如果您想按字母顺序排列列表，还可以添加order过滤器，并将其设置为"order": "gameName ASC"：

{ "where": {"mature":true, "categoryId": 1004}, "offset": 0, "limit": 5, "order": "gameName ASC" }

这将返回一个新的（第1页因为我将偏移设置为0）游戏数组，按gameName按字母顺序排列：

[
  {
    "mature": true,
    "gameName": "Battlefield4",
    "categoryId": 1004,
    "gameId": 1000055,
    "description": "Published by EA Digital Illusions",
    "publishedDate": "2013-01-01T00:00:00.000Z"
  },
  {
    "mature": true,
    "gameName": "CODBlacOps3",
    "categoryId": 1004,
    "gameId": 1000053,
    "description": "Published by Activision",
    "publishedDate": "2015-01-01T00:00:00.000Z"
  },
  {
    "mature": true,
    "gameName": "Destiny",
    "categoryId": 1004,
    "gameId": 1000057,
    "description": "Published by Bungie",
    "publishedDate": "2014-01-01T00:00:00.000Z"
  },
  {
    "mature": true,
    "gameName": "Evolve",
    "categoryId": 1004,
    "gameId": 1000054,
    "description": "Published by Turtle Rock Studios",
    "publishedDate": "2015-01-01T00:00:00.000Z"
  },
  {
    "mature": true,
    "gameName": "Rainbow6",
    "categoryId": 1004,
    "gameId": 1000056,
    "description": "Published by EUbisoft",
    "publishedDate": "2015-01-01T00:00:00.000Z"
  }
]

我能够如此快速地获得此结果的方式是使用API​​ Explorer。我分叉你的项目，更改了数据库连接值以匹配我的本地服务器，启动它然后转到http://0.0.0.0/explorer/#!/Games/Games_find，然后在游戏模型上使用不同的filter值：

enter image description here

答案 1 :(得分：2)

要向响应添加结果，请首先更改Category.mature远程方法返回给对象的响应类型：

Category.remoteMethod('mature', {
  accepts: [
    {arg: 'id', type: 'number', required: true},
    {arg: 'limit',type: 'number',required: false},
    {arg: 'after',type: 'number',required: false},
    {arg: 'before',type: 'number',required: false}   
  ],
  // mixing ':id' into the rest url allows $owner to be determined and used for access control
  http: {
    path: '/:id/games/mature',
    verb: 'get'
  },
  returns: {
    arg: 'games',
    type: 'object' // will be whatever you pass back as 2nd arg to callback()
  }
});

然后只需将您想要的值添加到新游戏对象中，使用现有的gamesArr作为data的值，并将值传入限制值，值之前和之后传入响应对象中作为成功回调的第二个参数：

callback(null, {
  "perPage": limit,
  "total": gameArray.length,
  "data": gameArray,
  "paging": {
    "cursors": {
      "after": gameArray[gameArray.length-1].game_id, // last game_id in result
      "before": gameArray[0].game_id // first game_id in result
    },
    "previous": "http://localhost:3000/api/Categories/1004/games/mature?before=" + gameArray[0].game_id,
    "next": "http://localhost:3000/api/Categories/1004/games/mature?after=" + gameArray[gameArray.length-1].game_id
  }
})

正如我提到的那些过多复杂代码的Games.find（）调用，你也不应该删掉该对象的3或4个副本。您可以在逻辑中包装对象的构造，然后进行单个callback（）调用以简化远程方法的I / O管理并编写更少的代码。减少到单个Games.find（）调用将使发送此结果更容易。

另请注意卷曲的撇号字符和制表符与空格缩进（选择一个并坚持使用，不要混合），在构建和组织代码时更容易帮助。

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